In recent years, an information terminal has been multi-functionalized through the advancement of a communication technology, and a portable information terminal that can be carried around, such as a smartphone and a tablet terminal, has appeared on the market. The portable information terminal not only transmits and receives e-mails but also has, as its standard function, a browser function of acquiring a document file written in a markup language, such as HTML and XML, from a web server connected to the Internet to view a web page. A majority of such portable information terminals are provided with, in addition to a button input function, touch panel means for enabling an input operation to be performed by, for example, touching the screen with his/her finger.
Also in an in-vehicle information terminal, such as a car navigation system mounted in an automobile, in-vehicle information terminals for enabling, in addition to conventional route search and television watching functions, collection of various types of information, such as transmission and reception of e-mails, viewing of a home page, and electronic commerce which use the Internet communication, have come into the market.
Incidentally, most of the users who own the automobile also own, along with the in-vehicle information terminal mounted in the automobile, a portable information terminal having a function of transmitting and receiving data by wireless communication. In order to use the Internet communication on the in-vehicle information terminal, the communication function is necessary to add functions of Internet access, acquisition of the latest information, and e-mails. However, paying communication expenses only for the in-vehicle information terminal, such as a car navigation system, by the user is difficult because a high cost is required.
Accordingly, many users have come to adopt a method involving connecting his/her own portable information terminal and in-vehicle information terminal to each other via an interface, such as a wireless LAN, Bluetooth (trademark), and a cable, to provide the in-vehicle information terminal with the communication function with use of the communication function of the portable information terminal.
There are known several patent documents disclosing technologies relating to such communication system for communication among a plurality of devices.
For example, in Patent Document 1, there is disclosed a configuration in which a mobile phone is connected to an information device, screen information to be displayed on the information device is displayed on a display device of the mobile phone, and the information device is remotely operated via a network. The mobile phone of Patent Document 1 provides a technology capable of remotely operating the information device with a high level of operability with use of operation buttons of the mobile phone.
Further, in Patent Document 2, there is disclosed an example of a system in which a portable device is connected to a display device to make use of a communication function of the portable device. The display device of Patent Document 2 has an object to make use of the communication function of the portable device without a user operating in hand the portable device connected via an interface.